3,5-ditert.butyl-4-hydroxybenzyl alcohol is an article of commerce, employed as an antioxidant of the hindered phenol type. The corresponding benzaldehyde is a desirable, reactive intermediate compound, used, for example, in the manufacture of pesticides of the benzylidenemalononitrile type.
Conversion of substituted benzyl alcohols to corresponding benzaldehydes by oxidation processes is known. (See for example, J. Org. Chem. v. 39, 3304 (1974) and J. Org. Chem. v. 26, 4814-16 (1961)). The oxidation of the alcohols involes problems with expensive reagents and disposal of inorganic waste products and yields, after purification, are not as good as desired. Oxidation of the corresponding benzyl chlorides is often considered to be a more economically attractive method of manufacturing the aldehydes. Another method of converting a limited class of benzyl halides of corresponding benzaldehydes is the Sommelet reaction in which the benzyl halide forms a quaternary salt by reaction with hexamethylenetetramine. The quaternary compound may then be hydrolyzed to yield the benzaldehyde and ammonia. The reaction is not a general one, sometimes failing for no apparent reason. (See "Survey of Organic Syntheses" by Calvin A. Buehler and Donald E. Pearson, pages 557-8, John Wiley & Sons, Inc. 1970) When this method is used to convert 3,5ditert.butyl-4-hydroxybenzyl chloride to the corresponding aldehyde, removal of colored, semi-solid impurities from the product is time-consuming and inefficient.